Is it possible to become immortal with the help of organ transplants? That was the unexpected topic of discussion this week between Chinese President Xi Jinping and Russian President Vladimir Putin when they met at a military parade in Beijing.
A translator, speaking in Mandarin on behalf of Putin, told Xi how human organs can be repeatedly transplanted 'so that one can get younger and younger' in spite of age, and might even be able to stave off old age 'indefinitely.'
It's predicted that in this century it might become possible to live to 150, he added.
Their smiles and laughter suggest it was a bit of banter, but might they be on to something?
Organ transplants certainly save lives - in the UK, over 100,000 people have been saved in the last 30 years, says NHS Blood and Transplant.
And continued advancements in medicine and technology mean transplanted organs are lasting far longer once in people.
Some patients have had a kidney transplant that has kept working for more than 50 years.
The lifespan of an organ depends on how healthy the donor and recipient is - plus how well they look after it.
Currently, people who get a new organ also have to take strong anti-rejection drugs called immunosuppressants for life. These can have side effects, such as high blood pressure, and increase the risk of infections.
Putin and Xi may be talking about having multiple organs transplanted and perhaps repeatedly.
Scientists are working on making rejection-free organs, using genetically-altered pigs as the donors.
Breeding special pigs is ideal, say experts, since their organs are roughly the right size for people. However, these are still experimental.
Beyond organ transplantation, approaches like plasma replacement are being explored, but results remain uncertain.
Ultimately, while damaged and diseased organs may be replaceable, the resilience of our bodies as we age can limit the viability and practicality of such strategies.
As Prof Mabbott suggests, rather than focusing on extending lifespan, it may be more beneficial to strive for healthy years lived.